I sure hope Overstock's opsec people are securing their bitcoin wallets. Worst news to hear would be that someone took their bitcoins out of their wallets the next day.
as soon as there's enough money, well funded organizations will start attacking, and robbing a bitcoin wallet is probably less risky than a bank...
They are probably one of the groups with the best BTC storage security (while maintaining usability). So yes, if they WERE to be robbed, then that would basically mean that no one is able to properly secure BTC.